1. Field of the Invention
The present invention relates to a device and a method for storing and administering active substances, e.g., medical or biochemical active substances.
2. Description of Related Art
Many variants are known for administering medications of various forms, e.g. medical or biochemical active substances. In addition to the use of commonly known syringes, microneedles are also, for example, proposed as a transfer means for the active substance into a skin.
There are in principle several important criteria that must be taken into account in this context. Among the important criteria are the mechanical stability and biocompatibility of the microneedles, but also the capability of storing sufficient quantities of active substances and administering them via the microneedles. Structures such as cavities or depressions can be disposed for this purpose inside the microneedles in order to store active substances.
U.S. Pat. No. 6,334,856 B1, for example, describes microneedles that have reservoirs for the storage of active substances. The reservoir is preferably disposed under the needles on the substrate side and connected via internal ducts, such as holes, to the internal region of the microneedles, with the result that active substances can be guided out of the reservoir and delivered through microneedles to a body that is to be treated.
To allow even relatively large quantities of active substances to be stored reliably, German patent application DE 10 2006 028782.7 (not previously published and therefore not prior art) proposes to dispose microneedles inside a package that forms the reservoir. The reservoir contains a carrier medium in which the active substance is present in dissolved form. The microneedles are thus embedded in the carrier medium having the active substance, and are thereby supplied with the active substance. Storage of the active substance in dissolved form can lead to problems, however, when the solubility limit of the carrier medium is reached. When the solubility limit of the carrier medium is reached and exceeded, precipitation of the solution then occurs and the active substance settles in solid form in the reservoir. In solid form, however, the active substance cannot be administered through the microneedles. The above-described concept thus comes up against a natural limit to the quantity of active substance that can be absorbed.